"Think of it this way," said the mother of a diabetic child. "The candles we light at my daughter's birthday party could ignite a torch of good eating habits for all the kids."

A bit rhetorical, perhaps, but the point she was making deserves vivid illumination. Children afflicted with diabetes are forced into food choices and patterns of eating that, we are coming to learn, are much closer to the way we should eat than is the contemporary American diet. There's no reason for parents or for the diabetic child to be embarrassed or defensive about what's on the table or in the lunch box; on the other hand, there's no reason not to serve cake at a birthday party.

Juvenile-onset diabetes - usually called just juvenile diabetes - is the most severe form of the "metabolic disorder" that interferes with or prevents insulin within the body from doing its work to transform carbohydrates (sugar and starch in food) into glucose. Despite the name, it may strike adults as well as children. Once it is diagnosed, the diabetic must take at least one daily injection of insulin and carefully balance it, food intake and exercise to keep a proper level of blood sugar. A less severe form of the disease is known as adult-onset diabetes.

Diabetes has been called a "closet disease." Because diabetics look healthy and can perform normally at work and play, there is no reason for others to know of their illness. Because of the stigma of having to take daily injections, many chose to hide it. But the closet door is being ripped open. An organization of concerned parents hopes to encourage more research and want their children to grow up free of shame and fear. Also, the closet has become too crowded. Over 10 million Americans now are diabetics and incidence is climbing at a rate of 6 percent a year.

A pamphlet for parents published by the Juvenile Diabetes Foundation, which has a local office in Silver Spring, contains this observation:

"How the patient's family - his mother and father, his sisters and brothers, his grandparents - handles this new intruder into the family circle makes all the difference in the way the child himself accepts or denies his diabetes and copes with its management."

Food intake is vital. The patient must eat on a rigid schedule, often requiring snacks as well as regular meals.Care must be taken, not only to avoid concentrated sweets such as candy and syrups, but to balance the diet. Such is the nature of the disease that the blood sugar level must become neither too high nor too low. According to the Foundation, ". . . it is important to consider sugar as a friend as well as an enemy, as sometimes a good as well as an evil, and to try to avoid unnecessary anxiety about so-called cheating."

So the diabetic child isn't forced into a narrow, terribly restrictive, one-way street as is a person on, for example, a salt-free diet. Some parents try to follow traditional menus, relying on careful counting of carbohydrates, and use artificial sweeteners to replace sugar. Several members of the foundations local chapter and a Children's Hospital dietitian who gathered recently for an informal symposium on the subject favor a different tack.

"The great percentage of parents are not informed about what makes a proper diet," said one of them. "Nutrition is one of the first doors to pull back when juvenile diabetes occurs. You must become intelligently familiar with the makeup of foods. You have to rethink the menu and realize you will serve a lot more cabbage than (Starch-filled) peas. You have to encourage moderation, to lower food expectations. You're really teaching good eating habits for the whole family."

The dietitian, Mary Bick, explained that adults have relatively constant energy needs and can go on an exchange system diet adapted as much as possible to their food preferences. Children, on the other hand, use energy at wildly varying rates (for such things as growing as well as playing), making a rigid diet "very difficult."

The "appetitie is a good indication of energy needs," she said, adding that an unmeasured diet can "work."

"You don't go around with exchange lists in you pockets," said another person. "You just learn it. It becomes instinctive." Exchange tables are dietary formulae that assign values to foods within groups such as protein, fats and carbohydrates. The object is to allow persons on restrictive diets to spread their chips around in chosing a meal without accidently exceeding their limits. But not all diets follow the same pattern. Nuts, shunned for their calories by those trying to lose weight, can be a boon to the diabetic child in search of a treat or snack.

Charity Ball, whose 15-year-old daughter, Lisa, participated in the discussion, brought up the subject of parties. She said the approach she has used is to serve enough "friendly foods," presented in an unusual manner, that the sugar-rich treat either isn't missed or is such a minor part of the food intake that it does not harm.

"I consider sugar an empty-calorie food," Bick said. "Most people don't need it. I recommend a diet with no concentrated sweets and don't encourage people to eat dessert after every meal. No one should feel they haven't finished eating if they haven't had ice cream or cake. The mother of a diabetic child shouldn't feel she has to prepare a dietetic dessert for every meal. A cookie after a balanced meal, some birthday cake or ice cream is okay, but it should be cosidered as a treat."

Stella Heffron, president of the local chapter, avoids artificial sweeteners. Instead she "cuts sugar way back" in cheesecakes and cookies (but not spongecakes) and carefully limits portions of the elaborate gourmet recipes her family enjoys. "You don't need a special cookbook," she said. "You only need to know food values and how to count." She totals carbohydrates, using Barbara Kraus's "Dictionary of Calories and Carbohydrates" as a reference, then divides by the number of portions.

Some of Charity Ball's party ideas and recipes follow, along with two recipes from "Just Declicious and Sugar Free," a booklet of "favorite sweets" published by the Juvenile Diabetes Foundation. Inquiries about the booklet and juvenile diabetes should be directed to the foundation, P.O. Box 48, Silver Spring, Md. 20907.

For a cowboy and Indian theme party, Mrs. Ball prepares "Drum Sticks," Buffalo food (a platter of raw vegetables) and Ranch fries. Children prepare their own coolers or floats, blending iced tea, diet drinks, fruit juice or lemonade with cut up fresh fruit and filled or flavored ice cubes of various colors (the Medicine Man's special). Possible fillings include cherries, lemon wedges, mint leaves; flavorings might include ginger and honey. For dessert: custard-filled eclairs (Custard's last stand).

To prepare drumsticks, allow 1 or 2 drumsticks per child. Brush each one with peanut oil, then roll in a mixture of grated parmesan cheese and bread crumbs (half cheese, half bread crumbs) plus oregano and minced parsley to taste. Bake in a preheated 350-degree oven for 45 to 50 minutes.

For 12-to-15-year-olds, she suggests a buffet of salads (ham, tuna, chicken), raw vegetables and cold cuts as part of a "Lock-Mess Special." Instead of sandwich bread, extra-large cream puff shells are cut open to house the fillings. Potato salad and "Lockness Sea Grapes" are extras and dessert is an ice cream mold in the shape of a dragon.

The shimmering sea grapes are created by allowing a canned pear half for each child. The pear half is patted dry, placed - cut side down - on waxed paper, then coated with a softened cream cheese that has been cut with mayonnaise until it spreads easily. The cheese acts as glue, so the entire surface can be covered with rows of seedless grape halves. Once decorated, the pear is lifted on a spatula and placed atop a lettuce leaf on a serving plate.

For a birthday brunch, she has made omelets with a choice of international fillings, plus a watermelon half filled with fruit and special milk shakes. PARTY MILK SHAKE (2 servings) 1 dash cinnamon 1 teaspoon sugar or the equivalent in artificial sweetener 2 tablespoons dry milk 1 cup skim milk 1/2 teaspoon vanilla extract 1/2 cup blueberries, strawberries, sliced peaches 12 ice cubes (about)

Place cinnamon, sugar, dry and skim milk, vanilla and berries in the bowl of a blender. Whirl and add ice cubes, 2 or 3 at a time, through top until mixture is thick. VANNILLA PUDDING (4 servings) 2 cups skim milk 1 teaspoon vanilla extract Pinch of salt Liquid sugar substitute to taste 2 tablespoons cornstarch 1 teaspoon tapioca (optional) 1 teaspoon cocoa, plus 2 extra teaspoons sugar substitute (optional)

Bring 1 3/4 cups of milk to a boil. Add vanilla, salt and liquid sugar substitute to taste.

Dissolve cornstarch in remaining 1/4 cup milk and add to mixture, along with optional tapioca or cococa. Bring to a boil and simmer on low heat for 5 minutes. Pour into serving dishes and cool.

One serving equals 3/4 cup skim milk.

From "Just Delicious and Sugar Free" OATMEAL DROPS (About 50 cookies) 1/2 cup margarine 3/4 cup brown sugar substitute 3/4 cup sprinkle sweet 1 egg, well beaten 1/2 cup water 1 teaspoon vanilla extract 1 cup all-purpose flour, sifted twice 1/4 teaspoon salt 1/2 teaspoon baking soda 1 2/3 cup quick oatmeal 1/4 cup raisins

Using a wooden spoon, cream margarine and both sugar substitutes. Add egg, water and vanilla. Blend together, mixture will be watery.

Sift together flour, salt and baking soda, add to mixture, blending well. Stir in oats and raisins.

Drop by tablespoons on greased cookie sheet. Bake in preheated oven at 350 degrees for 12 to 15 minutes.

Two cookies equal 1 fruit exchange and 1 fat exchange.